Note: The server will overwrite this setting when it stops, so make sure to stop the server, then change the setting, then start it again, otherwise your setting will be overwritten.
world/serverconfig/computercraft-server.toml
[http]
enabled = true
To make it the default in all worlds, set it in defaultconfig/computercraft-server.toml.
world/serverconfig/ftbchunks-world.snbt
max_claimed_chunks: 5000
max_force_loaded_chunks: 1000
Or whatever values you want.